class_docstr: Classification task.
  
  Examples:
      >>> classification_task = Classification(num_classes=2)
      >>> classification_task.metrics = ['precision']
      >>> classification_task.num_classes
      2
      >>> classification_task.output_shape
      (2,)
      >>> classification_task.output_dtype
      <class 'int'>
      >>> print(classification_task)
      Classification Task with 2 classes
docstr: :return: number of classes to classify.
docstr_tok: [":","return",":","number","of","classes","to","classify","."]
code: def num_classes(self) -> int:
      """:return: number of classes to classify."""
      return self._num_classes
  
file_path: MatchZoo/matchzoo/tasks/classification.py
imports: from matchzoo.engine.base_task import BaseTask
label_desc: Use image node_id 2 for calling the Classification obj's underlying member method code with example usage: obj.num_classes() and returns: self